Improvement in slide-valves for steam-engines



I PATENTED DEC. 1, 18 63. G.'BRISTOL. SLIDE VALVE FOR STEAM ENGINES.

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PATENT' OFFICE.

RICHARD (J, nursron, or CHICAGO, ILLINOIS.

--lMP R."O-VEME NT -I N SLIDE-VALVES oa- STEAMENGINES;

Specification forming part of Letters Patent'No. 40,781, dated December1, 1863.

v "To [111 whom it may concern 1 .lowing'is a full,' clear, and exactdescription ofthe same, reference being had to the accompanyingdrawings, forming part of this specifica-tion, in which-e. g a

' Figure 1 is a vertical longitudinal section showing the valve in itsfree state from the rollers. ,'Fig. 2=is asi'milar "section showing thevalve resting;,on the rollers, it "havin g ground itself down. ";?'Fig.3 is a side iew, one side of the steam-chest'removed. Fig. 4' 'isaninverted plan of the valve.

. My present inventioiris-designed to render more practicaland'economical the application of the anti-friction slide-valve patentedto me I at previous dates-to wit, June 21, 1859, reissued 'February.7,1860, and November 13,1860. The nature of my present improvementconsists in the employment of a slide-valve, whichis channeled orgrooved on its working-face transversely to its motion, in combinationwith anti-friction rollers, in such manner that the. valve will beself-fitting to its seat without any furthcrlabor upon the faces ofeither than simply planing the surfaces which are to come in contact. Italso consistsin an arrangement of. parallel ways.

To enable others skilled in the art-to malteand use my invention, I wilIproceed todescribe the same with reference to the drawings. is thevalve-seat, withthe usual ports leading to and from theengine-cylinderl. I B is the steam-chest, with horizontal-side ways-forthe valve to travel'u'p'on and'between.v

These ways are designated by the letters a'a, and the most practicalway'of'ap'plying them is to construct them of steel or other hard,

durable metal and fasten them in the lower side corners of the chest, sothat if they wear away they may be replaced. I

C is the slide-valve, witha bearing-way on each of its sides. Thesewaysare horizontal and are most practical when formed of steel or otherhard, durable metal, such metal being.

let into recessesv in the valve-casting, as indicated at b If, Figs. 3and 4. The working-face of the valve isjust wide enough to fit snugbetween the hearing-waysu a, and the extensions or bearing-ways 1) I)are so arranged that they extend over the ways a a, so as to fit snug tothesides of the steam'chest. The face of the valve beyond and forward ofthe central space or chamber a is channeled from one side to the other,as indicated at d d. The channels are narrow and close together, so thatnarrow ribs shall only existvbe'tween them. The ends of the channels areclosed by shoulders e e, so that steam shall -be"confined in them, andthus madeto aid in balancing the pressure acting on its 'top.- Thenarrow channels form a divided working-surface, which answers all theends of a'. broad continuous surface and enables meto accomplish the endI have in view. a a

.D'Darethe friction-rollers. They are set. upon tneways u menu when-ure"valve" is placed -i'n the chest: B are confined so as to have everyfreedom to roll, but, at the same timeare kept inproperplace andoperative positiom, The rollers haveno' journals, and

therefore they support the valve at their circumferences, andfltheweight ot the valve is transferred by them upon'the ways a a;-

Itwill, be seen that in'stead of constructing the valve intwo parts, asin my patent of June, 1859, or of using inclined planes, as in my pat-'ent of 'N ovember 13, 1860, for the purpose. of

adjustment, I now use straight parallel pieces "or ways. of hard metalfitted into wander the projecting lips or extensions above the rollers,

corresponding. in their plane to like pieces "fitted. into or upon thevalve seatnnder the rollers','the rollers traveling betweenthese y 4 p Iclaim nothing new here in hard-metal bearing-pieces, as a ibrmerpatentsecures the sameto'me, I p 1 To makethe valve self-fitting withoutgrind.

ing its face and the face of the seat, I have grooved; the face of. thevalve so that but a small portion of the surface will come in contactwith the -seat,-an-d thus, being reduced, will very readily wear awayun'derthe pressure to which the valve is subjected. There fore, whenfirst put on-the valve is left-a little free of the rollers, or sothatit rests directly upon theseat. Thus arranged, a few hours use issufficient to wear the valve down and grind it steam-tight; At thisstage the whole load will come upon the rollers, and if .the rollers orthe pieces between which they travel in it, it would take considerabletime for it to wear down, and therefore only a portion of the load'wouldbe carried on the rollers.. And, too, in this case the'grooves carrywith them over theseats and-bridges of the ports a thin stratum ofsteam, which to a large. extent counterbalancesthe pressure, on the backof the valve and thus relieves the load the rollers have to carry,thereby rende'ri n g them and the parts between which they travel morelasting. Itshould be understood that the relief afforded to thevalve bythd'entran'ee of steam into the grooves or channels-"d d ,is notsufficient to prevent frictional con tact between the valve and itsseat, and therefore ,thefleading design of thechanneled surface of thevalve is not afl'ected injnr'ionsly.

What 1 claim as my invention, and desire to secure'by Letters Patent,is- 1. The combination of theparallel overhang ingways formed in theends of the valve with the parallel ways of the seat, composed ofseparate meta], and'the friction-rollers, the said ways being in aplanecorrespon(ling with the face of the valve, substantially as and forthe purposes set forth. a

2; The valve, with its face grooved as described, in combinationwith thestraight or parallel ways, having rollers between them for the purposeof making the valve selfifitting'and relieving suchrollers in part fromthe load.-.'

-3. Constructing a valve with a grooved face, I and arranging the samewith respect ,to frictionrollers in such manner that it is free from therollersduring the self-fitting of the valve to-its seat, and afterward.is mainly supported upon the rollers and operates to always be thussupported, substantially as herein described. 1

v 4. The'com'bination of horizontal or parallel ways, friction-rollers,and grooved 'valve,s'ubstant-ially in the mannerand for the purpose ait. BRISTOL.

Withessesz' a a I B. BRIDGES, J A} Ho'IsINGToN.

